This is a core-laboratory-only protocol in which the DNA preparative core and EB virus-transformation core process samples submitted by the investigator, Dr. Cawthon. Blood samples are obtained by Dr. Cawthon in the homes of individuals over the age of 85 who represent the subjects under study. The objective of Dr. Cawthon's project is to identify human genes that determine slower rates of aging. To accomplish this, he is utilizing a technique known as a genetic linkage analysis to determine if variations at specific genetic loci influence the probability of occurrence of two major indicators of slower aging: late fertility in women (the ability to conceive a child naturally and give birth at age 43 or older) and longevity (survival to 85 years or older). Dr. Cawthon is studying candidate genes and anonymous areas of human chromosomes in approximately 200 long-lived sibling pairs, aged 85 or older.